Surface-active compounds used as coating aids for film-forming coating compositions

ABSTRACT

COATING COMPOSITIONS INCLUDING A HYDROPHILIC COLLOID AND AT LEAST ONE COMPOUND OF THE FORMULA:   R-8OCH2CH2)MOCO-A-SO3M   WHEREIN: M STANDS FOR HYDROGEN, AN ALKALI METAL ATOM, AMMONIUM OR ORGANIC AMMONIUM, A STANDS FOR ARALKYLENE OR ARYLENE, M STANDS FOR 0 TO 30, AND R STANDS FOR A BRANCHED-CHAIN ALIPHATIC GROUP OF 10 TO 20 CARBON ATOMS, ARE DESCRIBED. THE COATING COMPOSITIONS ARE PARTICULARLY USEFUL IN THE FORMATION OF PHOTOGRAPHIC SILVER HALIDE MATERIALS AND THE LAYERS COATED THEREFROM DO NOT EXIBIT HYDROPHOBIC AREAS LEADING TO REPELLENCY SPOTS OR COMETS.

United States Patent Oflice 3,788,852 Patented Jan. 29, 1974 70 Int. Cl. G03c 1/02, 1/38 US. Cl. 96-67 7 Claims ABSTRACT OF THE DISCLOSURE Coating compositions including a hydrophilic colloid and at least one compound of the formula:

M stands for hydrogen, an alkali metal atom, ammonium or organic ammonium,

A stands for aralkylene or arylene,

m stands for to 30, and

R stands for a branched-chain aliphatic group of 10 to 20 carbon atoms,

are described. The coating compositions are particularly useful in the formation of photographic silver halide materials and the layers coated therefrom do not exhibit hydropho bic areas leading to repellency spots or comets.

This invention relates to surface active compounds suitable for use as coating aids for film-forming coating compositions comprising a hydrophilic colloid, and to hydrophilic colloid compositions comprising said coating aids.

In the application of film-forming coating compositions comprising a hydrophilic colloid to surfaces, particularly in the photographic industry, it is desirable to apply such coating compositions uniformly and at good production speeds. In many cases it is even desirable to apply such coatings over other previous layers, which are either wet or dry.

It is necessary, in the photographic industry, that colloid compositions ready for coating are entirely hydrophilic to obtain a uniform layer therewith comprising no hydrophobic inclusions that may lead to repellency spots or comets in the said layer. Moreover, the entire surface of a layer formed from such colloid compositions should be hydrophilic so that it can be rewet readily either by the processing solutions if said layer is the top layer of a photographic material to be processed, or by the coating composition that will be applied to said layer for forming a next layer. Indeed, during processing, airbubbles are more easily carried along by a hydrophobic surface than by a hydrophilic surface, which air-bubbles will manifest themselves as small undeveloped areas in the processed material; moreover, when the material comprises hydrophobic inclusions so that its surface is not entirely hydrophilic but shows hydrophobic areas, water will not uniformly wet the said surface in that it is repelled at the hydrophobic areas and form drops thereon. After processing such materials cannot be dried uniformly. They show a poor retouchability when it is desired to retouch such-like materials.

In the case wherein the layer formed from the said colloid composition is overcoated with a following layer, the maximum speed of the moving layer to be overcoated, at which no repellency occurs can be increased, when and to the extent that the surface to be overcoated is more hydrophilic; local hydrophobic areas at the surface of the layer to be overcoated can give rise to the formation of so-called repellency spots or comets in the said next layer.-

Thus, in order to eliminate all these possible coating defects such as air bubbles repellency spots, or comets the use of coating aids has been widely adopted.

Saponin is conventionally used as coating aid for coating compositions comprising hydrophilic colloids. Though this product excels by its favorable anticomet action, it may vary markedly from batch to batch and is much more expensive than synthetic coating aids.

A number of synthetic surface active agents have been proposed for use as coating aids to facilitate the coating of compositions comprising hydrophilic colloids more particularly gelatin layers. Most of these coating aids do improve some properties of the layer. However, they adversely affect other desired properties. For instance, hydrophilic colloid layers comprising coating aids, which prevent the formation of comets in the said layers, may have an inadequate rewettability, which causes difiiculties in the processing of photographic elements or it may be difiicult to overcoat such layers when in wet state, which is quite undesirable especially in simultaneous multilayer applications. In order to overcome these disadvantages it has been proposed to use mixtures of coating aids having different properties.

It has now been found that surface active compounds corresponding to the following general formula:

M stands for hydrogen, an alkali metal atom such as lithium, sodium and potassium, ammonium or organic ammonium e.g. diethanol ammoniun, triethanol ammonium, triethyl ammonium and morpholinium,

A stands for aralkylene or arylene,

R stands for a branched-chain aliphatic group of 10 to 20 carbon atoms, preferably an aliphatic group of the formula wherein n is 0 or 1, R stands for hydrogen or when n=1 may be alkyl such as methyl and each of R and R stands for a straight-chain or branched-chain alkyl group or together represent the atoms necessary to close an alicyclic ring structure, and

m stands for 0 to 30,

are excellent inexpensive coating aids for use in coating compositions comprising a hyd-rophilic film-forming colloid such as gelatin.

The surface-active compounds according to the invention and corresponding to the above general formula can be prepared very easily as illustrated below by reaction of alicyclic alcohols or branched-chain alcohols (m=0) or such ethoxylated alcohols (m. is 1 to 30) with sulphocarboxylic anhydrides such as o-sulphobenzoic anhydride, o-sulphomethyl-benzoic anhydride and o-carboxymethylbenzene sulphonic anhydride. Preparations starting from sulphoaryl-carboxylic acids or acid chlorides and the alcohol, or transesterification reactions, are also possible.

As an example of an alicyclic alcohol from which coating aids according to the invention can be prepared hydroabietyl alcohol may be mentioned.

Examples of branched-chain alcohols that can be used are branched-chain aliphatic secondary alcohols such as commercially available isotetradecyl alcohol, i.e. 2-methyl-7-ethyl-4-undecanol and the widely known branched-chain primary oxo-alcohols having at least 10 C-atoms such as isodecyl alcohol, isotridecyl alcohol, isohexadecyl alcohol and isooctadecyl alcohol. Isodecyl alcohol is a commercial material prepared from C -ole fins (tripropylene) by means of the oxo-synthesis (cfr. H. R6mpp-Chemie Lexikon-Franck-sche Verlag, Stuttgart, Germany) and is a mixture of primary branchedchain C -alcohols. Isotridecyl alcohol is a commercial material prepared from C -olefins (triisobutylene, tetrapropylene or di(2-methyl-1-pentene)) by means of the oxo-reaction and is a mixture of primary branched-chain C -alcohols. Isohexadecyl alcohol and isooctadecyl alcohol are commercial materials prepared by aldol-condensation of C or C -aldehydes formed by oxo synthesis; isohexadecyl alcohol is a mixture of branched-chain primary C -alcohols mainly consisting of alcohols as represented by the formula I on-cmon Other branched-chain alcohols from which the coating aids of the invention can be derived are the branchedchain alcohols prepared by alkaline condensation using catalytic amounts of alkali such as potassium hydroxide at temperatures comprised between 200 and 300 C. (known as Guerbet Reactionsee e.g. Fette-Seifen- Anstrichmittel, 71, No. 3, pp. 215-218 (1969)) of a branched-chain or straight-chain alcohol with the same or other branched-chain or straight-chain alcohol.

More details regarding the preparation, the composition and properties of branched-chain oxo-alcohols, which can be used to form the coating aids according to the present invention, can be found in Fortschr. Chem. Forsch., Bd. 11/1, pp. 121-134.

Examples of coating aids suitable for use according to the present invention can be represented by the following formulae lSo-HuOxrO C O OzNa ) CH: CH:

I l i CH: CH: 1 CH: CH:

H1O C O O :Na

isonflon-o o o@ OzNa on-om-o 0 o--@ H oo a z): A l

(6) SOzNa 0 o 0 01H: l /CHo H C-(CHDHOHCHzCH; Hon,or r

('I) soon HaC-(C s)x- 2)r- Ha CHICHI) I 0 C wherein x+y=8 to 12 SO sNa wherein x+y:= 8' to 12.

The following preparations illustrate how the surfactants of the invention can be prepared.

COMPOUND 1 A solution of 48.4 g. of isohexadecyl alcohol (commercially available e.g. from Esso Belgium N.V., Antwerp, Belgium), 36.8 g. of o-sulphobenzoic anhydride and 15.8 g. of pyridine in 750 ml. of anhydrous benzene was refluxed for 8 h. whilst stirring. The resulting solution was treated with 11 g. of sodium carbonate in 300 ml. of water. The mixture was concentrated till dry by evaporation. The residue was dissolved in water and the solution was extracted with ethyl acetate. The aqueous solution was concentrated till dry by evaporation and the residue was dissolved in anhydrous ethanol, filtered, concentrated by evaporation, and dried.

Yield: 61 g.

COMPOUND 2 A solution of 54 g. of isooctadecyl alcohol (commercially available e.g. from Farbwerke Hoechst A.G., Frankfurt am Main-Hochst, Germany), 36.8 g. of o-sulphobenzoic anhydride and 158 g. of pyridine in 900 ml. of anhydrous benzene was refluxed for 8 h. whilst stirring. The resulting solution was treated with 11 g. of sodium carbonate in 300 ml. of water. The mixture was then concentrated till dry by evaporation. The residue was dissolved in water and the resulting solution was extracted with ethyl acetate. The aqueous solution was concentrated till dry by evaporation and the residue was dissolved in anhydrous ethanol, filtered, concentrated by evaporation, and dried.

Yield: 64 g.

COMPOUND 3 A solution of 50 g. of hydroabietyl alcohol, 31.5 g. of o-sulphobenzoic anhydride, and 13.5 g. of pyridine in 750 ml. of anhydrous benzene was refluxed for 8 h. whilst stirring. The resulting solution was treated with 9 g. of sodium carbonate dissolved in 300 ml. of water. The mixture was then concentrated till dry by evaporation. The residue was dissolved in anhydrous ethanol, filtered, concentrated again by evaporation, and dried.

Yield: 35 g.

Compounds 4, 5 and 6 were prepared in a similar way starting from isotn'decylalcohol, 2-butyloctanol and isotetnadecylalcohol respectively.

COMPOUND 7 A solution of 40.2 g. of an ethoxylated secondary synthetic C C aliphatic alcohol containing 3 recurring ethylene oxide groups per molecule and commercially available under the trade name Tergitol 15-S-3 from Union Carbide and Carbon, 18.4 g. of o-sulphobenzoic anhydride, and 7.9 g. of pyridine in 200 ml. of anhydrous toluene are refluxed for 8 hours whilst stirring. The resulting solution is treated with 5.3 g. of sodium carbonate dissolved in 200 ml. of water. The mixture is concentrated completely by evaporation. The residue is dissolved in water and the resulting solution is extracted with ethyl acetate. The aqueous solution is concentrated completely by evaporation and the residue is dissolved in anhydrous ethanol, filtered, and concentrated by evaporation.

Yield: 42 g.

COMPOUND 8 A solution of 100 g. of an ethoxylated secondary synthetic C -C aliphatic alcohol containing 9 recurring ethylene oxide groups per molecule and commercially available under the trade name Tergitol 15-8-9 from Union Carbide and Carbon, 29.5 g. of o-sulphobenzoic anhydride, and 12.7 g. of pyridine in 400 ml. of anhy drous toluene is refluxed for 8 h. whilst stirring. The resulting solution is concentrated by evaporation and the residue is dissolved in 1000 ml. of water and treated with 8 g. of sodium carbonate dissolved in 50 ml. of water. The resulting aqueous solution is extracted with ethyl acetate and concentrated by evaporation. The residue is dissolved in anhydrous ethanol, filtered, and concentrated by evaporation.

Yield: 106 g.

The coating aids according to the present invention promote the uniformity of coating and markedly reduce the tendency to form repellency spots. Coating compositions containing the coating aids of use according to the invention can be applied to dry surfaces as well as to wet surfaces and form layers that can be overcoated easily in wet as well as in dry state, the said layers being either light-sensitive layers or not. Light-sensitive hydrophilic colloid materials comprising these coating aids also show improved wettability by photographic processing liquids.

It may sometimes be advisable to use blends of two or more coating aids according to the present invention. Indeed, it is observed frequently that one coating aid according to the invention performs best in one respect e.g. as regards its anticomet properties, whereas another is definitely superior in a different eifect e.g. promoting uniformity of coating. These blends provide the major effects required and can often show characteristics superior to either coating aid alone. These effects may also result with blends of the coating aids of use according to the present invention with known coating aids such as saponin and other synthetic coating aids.

The coating aids of the present invention have also favorable properties for dispersing or emulsifying substances in hydrophilic colloid compositions, which as a result of the presence of said coating aids also show improved coating characteristics. For instance they are suitable as dispersing agent or emulsifying agent for substances that are to be incorporated into layers comprising a hydrophilic colloid and that would give rise to the formation of repellency spots in said layers when no compounds according to the invention were present.

Although the coating aids according to the present invention are mainly intended for use in coating compositions comprising gelatin as hydrophilic colloid, they can also be used as coating aid for coating compositions comprising other hydrophilic colloidal materials or mixtures of them, e.g. hydrophilic natural colloids, modified hydrophilic natural colloids or synthetic hydrophilic polymers. More particularly these colloids may be selected of such film-forming natural or modified natural hydrophilic colloids as e.g. glue, casein, zein, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, carboxymethyl hydroxyethyl cellulose, gum arabic, sodium alginate and hydrophilic derivatives of such colloids. They may also be selected of such synthetic hydrophilic polymers as e.g. polyvinyl alcohol, poly-N-vinyl pyrrolidone, polyvinyl amine, polyethylene oxide, polystyrene sulphonic acid, polyacrylic acid, and hydrophilic copolymers and derivatives of such polymers. In this connection reference is made e.g. to United Kingdom patent specification 1,139,891 and to French patent specification 1,507,874 which relate among others to heatand/ or pressure-sensitive materials comprising a recording layer mainly con sisting of a dispersion of hydrophobic thermoplastic poly mer particles in a hydrophilic colloid binder.

It has been found that coating aids according to the present invention improve the coating characteristics of coating compositions already at a concentration as low as 0.01% by weight relative to the weight of dry colloid. Larger concentrations, however, can also be used but generally the concentration is not higher than 5% by weight based on the weight of dry colloid.

The coating aids according to the invention are particularly suitable for use in a coating composition comprising gelatin as hydrophilic colloid, either as an aqueous solution of gelatin or as a photographic emulsion which ordinarily is composed of an aqueous solution of gelatin containing as the light-sensitive material therein, a silver halide such as silver bromide, silver chloride, silver iodide, or mixtures thereof or another light-sensitive substance. The emulsion may contain other substances such as sensitizing dyes, hardeners, stabilizers, p'H-adjusting compounds, color couplers, antifogging agents, development accelerators, thickening agents, developing agents, softening agents, or the like. For instance, the coating aids of the invention are useful in gelatin photographic emulsions, not only those, which are non-optically sensitized, but also in orthochromatic and .panchromatic emulsions. This also includes gelatin emulsions intended for color photography such as those containing color forming couplers and fine-grain emulsions of the Lippmann-type.

The coating aids of use according to the present invention and their mixtures with other coating aids are also very useful in various other types of coating compositions in which gelatin is an important constituent, for example, in gelatin coating compositions to be applied as antihalation layer to the back or front of the base in a photographic material, as protective layer, as filter layer, as intermediate layer, as anticurling layer etc., which layers can also contain all kinds of other ingredients such as filling agents, hardening agents, antistatic agents, antifriction agents, or in any type of gelatin layer, which is coated from a composition comprising an aqueous solution of gelatin.

The coating compositions in accordance with our invention may be coated on a transparent support e.g. of glass, cellulose esters, polyethylene terephthalate or on a nontransparent reflecting material such as of paper or an opaque cellulose ester. It is often desirable first to coat a subbing layer to the support, this practice of subbing being well known in the art.

The coating procedure may comprise any of the standard procedures employed in industry, such as roller coating, brush coating, dip-coating, spraying, using a doctor blade or an air blade to control the thickness anddistribution of the coating composition.

The following examples illustrate the present invention.

EXAMPLE 1 A series of three aqueous gelatin solutions comprising per kg. 50 g. of gelatin were prepared.

To each of these gelatin compositions a certain amount of coating aid was added as listed in the table below.

After having been coated on a conventional subbed cellulose triacetate support the number of repellency spots in the layer formed was counted.

The results found are listed in the following table.

Coating aid used per Repellency spots kg. gelatin solution: per sq. m.

15 m1. of a 12% aqueous solution of saponine (A) 22 (A)+10 ml. of a aqueous solution of compound 7 4 (A)+10 ml. of a 5% aqueous solution of compound 8 4 EXAMPLE 2 Example 1 was repeated with the difierence that now the coating aids listed in the following table were used.

Coating aid used per Repellency spots kg. gelatin solution: per sq. m.

ml. of a 12% aqueous solution of saponine (A 16 (A)+10 ml. of a 5% aqueous solution of compound 2 14 We claim:

1. A photographic element comprising a support and one or more water-permeable hydrophilic colloid layers including light-sensitive silver halide emulsion layers wherein one or more of said layers comprise a surfaceactive compound corresponding to the formula:

8 wherein n is 0 or 1, R stands for hydrogen or when n=1 may be alkyl and each of R and R stands for a straight-chain or branchd-chain alkyl group or together represent the atoms necessary to close an alicyclic ring structure.

3. A photographic element according to claim 1, wherein in the formula A is phenylene.

4. A photographic element according to claim 1, wherein said compound is present in the said layer(s) in an amount of from 0.01 to 5% by weight based on the weight of dry colloid in the said layer(s) 5. A photographic element according to claim 4, wherein said colloid is gelatin.

6. A photographic element according to claim 1, where in said water-permeable colloid layer comprising the said surface-active compound is a light-sensitive gelatino silver halide emulsion layer.

7. A photographic element according to claim 1, wherein the said water-permeable colloid layer comprising the said surface-active compound is a gelatin protective antistress layer coated over a light-sensitive silver halide emulsion layer.

References Cited UNITED STATES PATENTS 3,026,202 3/1962 Knox 96114.5 3,415,649 -12/1968 Nishio 106-125 3,525,620 8/1970 Nishio 96-114.5

FOREIGN PATENTS 747,801 4/1956 Great Britain 96-94 R I. TRAVIS BROWN, Primary Examiner A. 'r. SURO rrco, Assistant Examiner US. 01. X.R. 

